Method of finning engine cylinders



June 7, 1949. w. M. sus'se:

METHOD OF FINNING ENGINE CYLINDERS 2 Sheets-Sheet 1 Filed April 17. 1944IN VEN TOR.

w w m M M June 7, 1949. w. M. BUSSE 2,472,245

METHOD OF Fmume ENGINE CYLINDERS Filed April 17, 1944 2 sna -sheet 2 1/]I/l/ III/II I [M INVENTOR.

WILL/AM MEI/J55 A TTOR NE YS Patented June 7, 1949 2,472,245 METHOD OFFINNING ENGINE CYLINDERS William M. Busse,

The Griscom Russell This invention relates to methods for making enginecylinders, particularly cylinders for high- .compression, air-cooledaviation engines, and has for its object to provide a method for makingcylinders having a highly extended heat-radiating surface whereby dangerof failure of the engine from overheating is greatly reduced. It is wellknown that the power output of aviation engines per cubic inch ofcylinder capacity has been greatly increased by recent developments inengine structure to obtain high compression, and also by the developmentof new fuels. This increase in the power produced per unit of cylindercapacity must be accompanied by an increase in heat-radiating capacityto prevent failure of the engine from overheating.

It has heretofore been the general practice to form by casting ormachining, heat-radiating fins directly on and integral with thecylinder wall or with a sleeve which is shrunk or otherwise attached tothe cylinder. Such process, however, has limitations in the amount ofextra radiating surface that can be provided, and cylinders soconstructed cannot be safely employed and obtain the power output whichis obtainable in liquidcooled engines of equal cylinder capacity.

The principal object of the present invention is to provide a method forproducing an engine cylinder having a greatly extended heat-radiatingsurface, rapidly and efliciently on a mass production scale.

A further object of the invention is to provide an apparatus for use incarrying out my improved method which is of simple design, easilyconstructed, and foolproof in operation even in the hands of relativelyunskilled workmen.

Briefly stated, my improved method consists in forming from a flat metalribbon a helically finned sleeve of a diameter to fit the cylinder andMassillon, Ohio, assignor to Company, New York, N. Y., a corporation ofDelaware Application April 17, 1944, Serial No. 531,419

1 Claim. (Cl. 29157.3)

thereafter soldering or otherwise attaching the sleeve to the cylinderwall. The ribbon, preferably of coppered aluminum, is drawn throughforming dies or rollers to form on one edge of the ribbon an L-shapedfoot with a short flange parallel with the .main portion of the ribbon.The ribbon so shaped is tightly coiled to produce, in efiect, asubstantially rigid tube from which short sleeve sections are cut andsoldered to the wall ofthe engine cylinder in the same manner that castsleeves having integral fins are now employed when it is desirable toprovide a heatradiating surface of cylinder itself.

In the accompanying drawings,

different metal from the Figure 1 is a side view partly in section or amachine for carrying out my improved method;

Figs. 2 and 3 are sections on lines 2-: and 3-3, respectively, of Fig.1;

Fig. 4 is an enlarged sectional view of a portion of Fig. 3;

Figs 5 and 6 are sectionalviews on lines 5-! and 6-4 of Fig. 1;

Fig. 7 is a side elevation partly in section of a cylinder manufacturedin accordance with my improved method; and

Fig. 8 in a detail section on of a portion of the cylinder shown in Fig.7.

In Fig. 1 I have illustrated an apparatus for shaping the ribbon andcoiling it into a continuous sleeve or tube. As shown, the ribbon i issupplied from a spool 5 set on a vertical axis from which it passesbetween successive pairs of forming rolls. As here shown, two pairs ofrolls 6 and 1, respectively, are employed, but ad ditional pairs ofrolls may obviously be used if necessary or desirable in. the shaping ofthe ribbon. The thickness and stiffness of the metal employed for thefin determines the number of rolls necessary or desirable to bend theedge of the ribbon to the desired shape. As shown, the rolls 6 bend oneedge Z of theribbon to a right angle with the main width of the ribbon,second pair of rolls 1 form a narrow flange 3 on the edge of the rightangle portion 2 to thereby form a spacer flange having a flat radialcontacting surface for engagement with the radial face of the adjacentroils I and I are preferably supported so as to be rotated by the ribbonas the ribbon is drawn through the rolls. The rolls 6 end 'I may ofcourse be driven if desired, but in the preferred method of carrying outmy invention the rolls are not driven but serve to apply to the ribbonsuillcient drag to insure a tight winding of the ribbon on the mandrel8.

The supply reel 5 and rollers B and I are preferably supported on alongitudinally movable carriage 9, supported, for example, on guide rodsl0 extending parallel with the mandrel. The carriage is shifted by afeed screw H.

The mandrel 8 is continuously rotated through a suitable gear mechanism,not shown, and the relation of the rotary motion and the axial motion ofthe carriage is such that the mandrel, during each rotation, is shiftedthe exact width of the L-shaped foot of the ribbon.

To insure an even winding of the ribbon on the mandrel I preferablyprovide adjacent the manan enlarged scale I while the portion of theribbon. The

drel a fixed backing block i2 which extends from a point adjacent thetop of the mandrel to a point near the last pair of shaping rolls 1.Also adjacent the mandrel is a guide roller (3 having a convex peripheryshaped to fit the space between the up-turned margin 3 and the adjacentface of the fin. The backing block I! serves to hold the ribbon in itsdirect path of movement from the forming rollers to the mandrel andprevents any outward buckling of the ribbon due to the resistance of thecoiling operation. The backing block preferably has a. groove in itsunder surface for receiving the upper edge of the fin. In some instancesit may be advantageous to have the groove in the backing block deepenough to receive a substantial width of fin. Also the backing blockwith a groove embracing a substantial portion of the fin may be extendedpartly around the mandrel to guide and support the fin-during theinitial winding operation.

In operation the end of the ribbon is initially shaped by handthroughout a length sumcient to reach from the rolls to the mandrel, aportion of the ribbon being of intermediate shape to conform with theperipheries of the rolls 6. The ribbon is then threaded through therolls and attached to the mandel which is rotated while the carriage 9is advanced axially as described, thereby winding the ribbon on themandrel to form a continuous tubing the length of which is limited onlyto the length that it is expedient for the mandrel.

After the tube or sleeve is finished it may be cut into sections ofproper length for the cylinders to which it is to be attached, and thesesections are then fitted over the cylinder and attached to the cylinderin the usual manner, for example, by soldering. The sleeve of thehelically wound fin is particularly suitable for soldering for thereason that the meeting edges of the fin proper and the out-turnedflange 3 of the L-shaped foot form on the inside of the sleeve acontinuous shallow groove into which the melted solder expands, therebyforming a tight joint. If desired to increase the interlocking betweenthe solder and the fin the L-shaped foot 3 may be perforated atintervals in the portion of the foot parallel with the cylinder wall, asindicated at 4.

Any approved method of soldering the sleeve to the cylinder may beemployed. For example, the outer surface of the cylinder may be providedwith an external covering of solder before the sleeve is applied, or themolten solder may be forced by pressure between the outer surface of thecylinder wall and the inner surface of the sleeve. In this case themandrel used for forming the sleeve will be sufficiently larger than thecylinder to provide a space of the desired width to receive the solder.

Before cutting the sleeves for the individual cylinders from the lengthof tubing, it may be desirable to fasten, as by spot welding, theoutwardly-turned flange 3 of the L-shaped 'foot to the adjacent face ofthe fin with which the flange is in contact. Two such spot welds aremade, one

on each side of the point where the sleeve for the engine cylinder is tobe cut off from the length of tubing.

Instead of soldering the sleeve sections to the engine cylinders theymay be shrunk onto the cylinders or welded. High melting point solder,however, forms a joint of ample strength and also of highheat-conductivity, and is entirely satisfactory, particularly with a finformed of coppered aluminum, as described.

Instead of winding the formed ribbon directly from a straight lengthonto the mandrel I may. if desired, particularly if the fin material ishard and not easily bent, employ a fin-coiling machine intermediate theforming rolls 1 and the mandrel, to thereby pre-coil the fin into aspiral and thereafter wind the spiral tightly on the mandrel. Suchpre-coiling machine is shown in U. S. Patent No. 1,878,233 forpre-colling a fiat ribbon into a fin for subsequent application to apipe or tube as a heat radiating element. Such a machine may withappropriate modification be employed to pre-coil a shaped ribbon, and asa modification of the present process I may, if desired, pre-coil theL-shaped fin and then apply the pre-coiled fin to the mandrel to therebyform a sleeve from which sections for application to the cylinder wallmay be cut in the manner described.

In the drawing I have illustrated the mandrel as a solid shaft of thedesired diameter, but if desired to facilitate the withdrawal of themandrel from the sleeve or tube formed by the coiling of the ribbon, acollapsible mandrel of improved design may be employed. For example, themandrel may be made of three sections with themiddle section slightlytapered so that the relative axial movement of the middle section to thetwo outer sections will collapse the mandrel sufilciently to release thesleeve.

In carrying out the manufacturing operations on a commercial scale it isexpedient to manufacture the finned sleeves in convenient lengths forhandling and shipment, for example, ten or twelve feet. The labor costof manufacturing these sleeves is quite moderate. The winding machinescan be operated at about the same speed as the ordinary fin-windingmachine and require practically no attention other than the removal ofthe finished sleeve, the return of the carriage to its initial positionand the re-attachment of the cut oil end of the ribbon to the mandrel.

The sleeve lengths can then be sent to the engine factory where thq arecut in sections as needed and soldered or otherwise attached to theengine cylinders. The finned sleeve may be attached not only to thecylinder proper but also to the cylinder portion of the cylinder head,as shown in Fig. 7. Also, of course, the sleeve sections may be appliedto other apparatus than engine cylinders wherever it is desired to addheat transfer surface to a unit having a cylindrical wall.

It will also be understood that the finned sleeves may be made inlengths greater than the length of the mandrel by the simple expedientof collapsing the mandrel when the carriage reaches a point near its endand returning the carriage to the other end of the mandrel and forming asecond section of sleeve without cutting off the ribbon.

It will be further understood that the method may be otherwise modifiedwithin the scope of the appended claim.

I claim:

In the method of forming cylinders for engines and the like, the stepswhich comprise helically winding a strip of metal of L-shapedconfiguration to form a continuous sleeve of indefinite length with thefoot portions of the L in contact fastening said section as a unit tothe exterior of an engine cylinder.

M. BUSSE.

REFERENCES MT!!!) The iollowingreferences are of record in the file ofthis patent:

UNITED STATES PATENTS Nwnber Name 955,239 Farles Date my 28, 190'?Number 5 Name Date Miller July 16, 1912 Steenstrup' June 24, 1924 WayApr. 5, 1927- Price May 1'7, 1927 Berg May 1,1928 Dewald Sept. 20, 1932Bundy Feb. 7, 1933 Gay Aug. 7, 1943 Rodeck Apr. 3, 1945

